APA (7th ed.) Citation

Palmer, A. (1979). The Penguin dictionary of twentieth century history. Penguin Books.

Chicago Style (17th ed.) Citation

Palmer, Alan. The Penguin Dictionary of Twentieth Century History. Harmondsworth: Penguin Books, 1979.

MLA (9th ed.) Citation

Palmer, Alan. The Penguin Dictionary of Twentieth Century History. Penguin Books, 1979.